As a cyclist you are a vulnerable road user. You are often "invisible" to others.
If you are knocked off your cycle you may be in a position to claim against the responsible party's insurance.
You should, as with all other claims, get as much information about the other party as possible - particularly their registration number.
To help prevent an accident you should wear high visibility clothing, use cycle lanes wherever possible, wear a helmet and do not wear headphones which reduce your ability to hear what is going on around you.